Design Approach to Determine Shear Capacity of Reinforced Concrete Beams Shear Strengthened with NSM Systems

AbstractThis paper presents a design approach to predict the shear capacity of RC beams strengthened with fiber reinforced polymer (FRP) laminates/rods applied according to the near-surface mounted (NSM) technique. The new approach is based on simplified modified compression field theory (SMCFT) and considers the relevant features of the interaction between NSM FRP systems and surrounding concrete, such as debonding and concrete fracture. In the SMCFT model, the shear strength of an RC element is a function of two parameters, the tensile stress factor in the cracked concrete (β), and the inclination of the diagonal compressive stress in the web of the section (θ). However, this approach is not a straightforward design methodology due to its iterative nature. A sensitivity analysis is carried out to assess the relative importance of each input parameter that mostly affect the shear capacity of RC beams shear strengthened according to the NSM technique. Equations to determine β and θ without resorting to an iterative procedure are derived. The experimental results of 140 beams shear strengthened with NSM FRP are used to appraise the predictive performance of the developed approach.